package com.lodh.administrator.rcp.commands;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.eclipse.core.commands.ExecutionException;
import org.eclipse.e4.core.di.annotations.Execute;
import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.swt.widgets.Display;
import org.eclipse.ui.internal.ExceptionHandler;

public class SelectAllHandler extends WidgetMethodHandler {

	/**
	 * The parameters for a single point select all.
	 */
	private static final Class[] METHOD_PARAMETERS = { Point.class };

	
	public SelectAllHandler() {
		methodName = "selectAll";
	}
	
	@Execute
	public final Object execute() throws ExecutionException {
		final Method methodToExecute = getMethodToExecute();
		if (methodToExecute != null) {
			try {
				final Control focusControl = Display.getCurrent().getFocusControl();

				final int numParams = methodToExecute.getParameterTypes().length;

				if ((focusControl instanceof Composite) && ((((Composite) focusControl).getStyle() & SWT.EMBEDDED) != 0)) {

					// we only support selectAll for swing components
					if (numParams != 0) {
						return null;
					}

					/*
					 * Okay. Have a seat. Relax a while. This is going to be a
					 * bumpy ride. If it is an embedded widget, then it *might*
					 * be a Swing widget. At the point where this handler is
					 * executing, the key event is already bound to be
					 * swallowed. If I don't do something, then the key will be
					 * gone for good. So, I will try to forward the event to the
					 * Swing widget. Unfortunately, we can't even count on the
					 * Swing libraries existing, so I need to use reflection
					 * everywhere. And, to top it off, I need to dispatch the
					 * event on the Swing event queue, which means that it will
					 * be carried out asynchronously to the SWT event queue.
					 */
					try {
						final Object focusComponent = getFocusComponent();
						if (focusComponent != null) {
							Runnable methodRunnable = new Runnable() {
								public void run() {
									try {
										methodToExecute.invoke(focusComponent, null);
										// and back to the UI thread :-)
										focusControl.getDisplay().asyncExec(new Runnable() {
											public void run() {
												if (!focusControl.isDisposed()) {
													focusControl.notifyListeners(SWT.Selection, null);
												}
											}
										});
									} catch (final IllegalAccessException e) {
										// The method is protected, so do
										// nothing.
									} catch (final InvocationTargetException e) {
										/*
										 * I would like to log this exception --
										 * and possibly show a dialog to the
										 * user -- but I have to go back to the
										 * SWT event loop to do this. So, back
										 * we go....
										 */
										focusControl.getDisplay().asyncExec(new Runnable() {
											public void run() {
												ExceptionHandler.getInstance().handleException(
														new ExecutionException("An exception occurred while executing " //$NON-NLS-1$
																+ methodToExecute.getName(), e.getTargetException()));
											}
										});
									}
								}
							};

							swingInvokeLater(methodRunnable);
						}
					} catch (final ClassNotFoundException e) {
						// There is no Swing support, so do nothing.

					} catch (final NoSuchMethodException e) {
						// The API has changed, which seems amazingly unlikely.
						throw new Error("Something is seriously wrong here"); //$NON-NLS-1$
					}
				} else if (numParams == 0) {
					// This is a no-argument selectAll method.
					methodToExecute.invoke(focusControl, null);
					focusControl.notifyListeners(SWT.Selection, null);

				} else if (numParams == 1) {
					// This is a single-point selection method.
					final Method textLimitAccessor = focusControl.getClass().getMethod("getTextLimit", NO_PARAMETERS); //$NON-NLS-1$
					final Integer textLimit = (Integer) textLimitAccessor.invoke(focusControl, null);
					final Object[] parameters = { new Point(0, textLimit.intValue()) };
					methodToExecute.invoke(focusControl, parameters);
					if (!(focusControl instanceof Combo)) {
						focusControl.notifyListeners(SWT.Selection, null);
					}

				} else {
					/*
					 * This means that getMethodToExecute() has been changed,
					 * while this method hasn't.
					 */
					throw new ExecutionException("Too many parameters on select all", new Exception()); //$NON-NLS-1$

				}

			} catch (IllegalAccessException e) {
				// The method is protected, so do nothing.

			} catch (InvocationTargetException e) {
				throw new ExecutionException("An exception occurred while executing " //$NON-NLS-1$
						+ getMethodToExecute(), e.getTargetException());

			} catch (NoSuchMethodException e) {
				// I can't get the text limit. Do nothing.

			}
		}

		return null;
	}

	/**
	 * Looks up the select all method on the given focus control.
	 * 
	 * @return The method on the focus control; <code>null</code> if none.
	 */
	protected Method getMethodToExecute() {
		Method method = super.getMethodToExecute();

		// Let's see if we have a control that supports point-based selection.
		if (method == null) {
			final Control focusControl = Display.getCurrent().getFocusControl();
			if (focusControl != null) {
				try {
					method = focusControl.getClass().getMethod("setSelection", //$NON-NLS-1$
							METHOD_PARAMETERS);
				} catch (NoSuchMethodException e) {
					// Do nothing.
				}
			}
		}

		return method;
	}
}